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78 lines
1.2 KiB
Go
78 lines
1.2 KiB
Go
package ac
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import "math"
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type byteClassRepresentatives struct {
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classes *byteClasses
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bbyte int
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lastClass *byte
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}
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func (b *byteClassRepresentatives) next() *byte {
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for b.bbyte < 256 {
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bbyte := byte(b.bbyte)
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class := b.classes.bytes[bbyte]
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b.bbyte += 1
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if b.lastClass == nil || *b.lastClass != class {
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c := class
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b.lastClass = &c
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return &bbyte
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}
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}
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return nil
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}
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type byteClassBuilder []bool
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func (b byteClassBuilder) setRange(start, end byte) {
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if start > 0 {
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b[int(start)-1] = true
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}
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b[int(end)] = true
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}
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func (b byteClassBuilder) build() byteClasses {
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var classes byteClasses
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var class byte
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i := 0
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for {
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classes.bytes[byte(i)] = class
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if i >= 255 {
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break
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}
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if b[i] {
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if class+1 > math.MaxUint8 {
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panic("shit happens")
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}
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class += 1
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}
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i += 1
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}
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return classes
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}
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func newByteClassBuilder() byteClassBuilder {
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return make([]bool, 256)
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}
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type byteClasses struct {
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bytes [256]byte
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}
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func singletons() byteClasses {
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var bc byteClasses
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for i := range bc.bytes {
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bc.bytes[i] = byte(i)
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}
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return bc
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}
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func (b byteClasses) alphabetLen() int {
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return int(b.bytes[255]) + 1
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}
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func (b byteClasses) isSingleton() bool {
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return b.alphabetLen() == 256
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}
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